湘南四个金属矿田的区域重磁异常特征

湘南位于南岭构造带中段偏北地区,区内地层较齐全,岩浆岩活动频繁,褶皱、断裂发育,矿产十分丰富,大型—特大型内生多金属矿田比较集中,为华南重要的找矿远景区之一。

CHARACTERISTICS OF REGIONAL GRAVITY ANDMAGNETIC ANOMALIES OF FOUR MAJORPOLYMETAL ORE HELDS INSOUTHERN HUNAN,CHINA

Basaed on the interpretation of the regional gravity and magnetic picture of Southern Hunan, the paper presents a general chracterization of regional geophysical and geochemical anomalies of four major polymetal ore fields, namely, the Shuikoushan, Dongpo, Yaoganxian and Huang-shaping, in the light of lithology, regional tectonics, geology at depth, and magnetic activities. It is postulated that the important factor dominating the formation of major ore fields in southern Hunan was the intersection of regional structures cut through by faultings at great depth. It is also noted that the major ore fields are situated close to the zones of "magnetic high", and are often accompanied by characteristic geochemical anomalies with remarkable area! extension, high metal content, and of multielement composition. Various minor magnetic and gravity features, in the meantime, are often indicative of individual local ore deposits.It is evident from the study of the four known ore fields that regional gravi-ty and magnetic data can provide important information regarding the rock and ore-controlling stuctures, as well as other useful information for the metal-logenetic forecasting of the area. Emphasis is given to the close relationship between the west-east running Chengxian-Guiyang zone of magnetic high and the major ore occurrences. Special attention is called to where the zone meets the Lanshan-Lingxian gravity gradient belt, for this is where the major ore fields are centered.It remains an important task for geophysicists to pursue further investigations into the nature of the regional gravity and magnetic anomalies in order to gain still better results in mining geophysical exploration.